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How to Identify a Marijuana Cultivation Site, and What to Do

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Trees in Six Rivers National Forest were killed to allow sunlight to bath marijuana plants growing below the canopy | Photo courtesy of the U.S. Forest Service

Wandering deep into wilderness may not always result in peaceful surroundings. That's the message the Forest Service this week issued nationally, urging hikers and outdoor travelers to keep an eye out for marijuana cultivation sites. That should resonate here because California is no stranger to such activity.


In 2010 alone, forest officials eradicated 3,024,352 marijuana plants throughout the the 18 national forests in California. In 2009, they collected even more, some 3.6 million plants (and think about this: these numbers do not include state parks, national parks or land under the Bureau of Public Management).

Topping the list for last year was Shasta Trinity National Forest with over a half million plants discovered within its borders. More locally, San Bernardino came in at number three (377,186 plants) followed by Los Padres (311,503) at five and Angeles at seven (232,577).

The last time a warning was sent out was in 2009, but no specific incident prompted this year's message, explained John Heil of the Forest Service's Pacific Southwest office. "It's more of a safety message," he said, noting that there have been rare instances where the public or an employee has found themselves in a situation.

Heil said hikers who stay on trail will probably not encounter cultivation sites, which in California have typically been off the beaten path on rugged and rough terrain that is difficult to access.

How to Identify a Cultivation Site

The Forest Service lists these clues that may help you identify a cultivation site:

  • Sometimes marijuana smells like a skunk on hot days.
  • Hoses or drip lines located in unusual or unexpected places.
  • A well-used trail where there shouldn't be one.
  • People standing along roads without vehicles present, or in areas where loitering appears unusual.
  • Grow sites are usually found in isolated locations, in rough steep terrain.
  • Camps containing cooking and sleeping areas with food, fertilizer, weapons, garbage, rat poison, and/or dead animals.
  • Small propane bottles, used to avoid the detection of wood smoke.
  • Individuals armed with rifles out of hunting season.

What To Do

"As soon as you become aware that you have come upon a cultivation site, back out immediately," instructs the Forest Service alert. "Never engage the growers as these are extremely dangerous people.  If you can identify a landmark or record a GPS coordinate, that's very helpful.  The growers may be present and may or may not know that you have found their grow site."

"Get to a safe place and report as much detail about the location and incident as you can recall to any uniformed member of the Forest Service or to your local law enforcement agency," the instructions continue. "Leave the way you came in, and make as little noise as possible."

How Sites Affect the Environment

A marijuana plant may be natural to the earth, but farming them in a national forest has caused "extensive and long-term damage to ecosystems" and impacted public drinking water supplies hundreds of miles away in cities, according to the Forest Service.

"Growers clear native vegetation before planting and sometimes use miles of black plastic tubing to transport large volumes of water from creeks that are often dammed for irrigation," the alert explains. "The use of banned herbicides and pesticides by marijuana growers kill wildlife and competing vegetation.  This loss of vegetation allows rain water to erode the soil and wash poisons, human waste, and trash from the grow sites into streams and rivers."

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